1. Field
Example embodiments relate to a method of operating a semiconductor device, for example, to a method of operating a nonvolatile memory device using resistance nodes.
2. Description of the Related Art
A nonvolatile memory device, for example, a phase-change memory (PRAM) or a resistance memory (RRAM) may operate using variable resistance of resistance nodes. Because semiconductor products managing large quantities of data have increased capacity, the integration or the number of operating bits of nonvolatile memory devices may need to be increased. Nonvolatile memory devices that can operate in a multi-bit mode may be desirable for this integration.
Nonvolatile memory devices may have higher operating speeds as the capacity of the nonvolatile memory devices increases. Fast data processing may be required to manage large quantities of data. An increase in the operating speed of nonvolatile memory devices, for example, block erasing or flash erasing in flash memories, may be required for this data processing.
Because integration of nonvolatile memory devices may increase, attempts have been made to reduce the operating current. Nonvolatile memory devices using resistance nodes may need a higher operating current. A reduction in the operating current may affect variable resistance of resistance nodes. Related art nonvolatile memory devices may have limits in reducing the operating current.
For example, a phase change memory device may store data using variation in resistance according to the change of a crystal state of a phase change resistance element. To change the crystal state of a phase change memory device, higher current density may be required, and the operating current may increase. An increase in the operating current may generate a short channel effect, which may hinder integration of the phase change memory device. A region of the phase change resistance element in which the crystal state is changed may need to be reduced to obtain higher current density with a lower operating current.